HD Radio: So you Want More than One Signal?

So you want more than one signal?

By Ed McDade

As a former radio station owner, I can understand the frustration of having one frequency and needing more to really bring the message to the audience while trying to keep the expenses under control.  Let’s face it, buying additional stations is expensive and often not an option.

AM stations have had an unprecedented opportunity with the FCC AM revitalization and associated auctions.  Many AM stations were able to take advantage of AM revitalization and now enjoy an FM translator.  That has helped AM stations by giving them a clear(er) nighttime signal and in some cases, a signal period for those who had to sign off at sunset or have low nighttime power levels.

However, even with a translator, LPFM, or FM facility there is still only one format per frequency to serve a single audience.

So what are our options???

HD radio may be a viable option.  For stations who have a full-service FM license (any FM station that is NOT an LPFM or translator), there is the option of adding digital to your signal and generating multiple audio channels on the same frequency.  When what is now referred to as HD radio originated, it was known as IBOC, “In Band On Channel”.   In simple terms, the normal analog signal continued to operate as it has since FM began but now digital carriers were added above and below the analog portion of the licensed frequency making use of the full 200 kilohertz channel.

How does FM HD work?

FM HD transmission (broadcast) still uses the standard analog broadcast signal in addition to the HD components. When broadcasting FM HD (and using an HD receiver), we can still listen to the analog signal as we always have.  In addition, we can now hear CD quality audio on HD1.  On an analog radio, we are accustomed to seeing the frequency (for example) 97.1. On a digital receiver, we would see 97.1-1 which is the digital version of the stations analog signal.  If there are supplemental channels (secondary formats), we would see 97.1-2, or -3 or -4 depending on the number of supplemental channels which are broadcasting.

Yes, you read that correctly, 4 channels.  On a single FM frequency, now available are the “primary” audio signal (analog and HD1)along with up to 3additional signals.  These additional signals can all be music or talk or a mixture.  They can be originated “in house” or external.

What is involved?

Not to be the bearer of bad news but while digital broadcast adds lots of capability keep in mind it is not as “plug and play” as some would think. There are several considerations to take into account before making the switch.

Here are some considerations that we will touch on briefly in the following segments.

• To receive an HD FM signal you will need a different receiver (tuner)
• Additional or replacement transmitter
• Current broadcast antenna
• Possible replacement of microwave equipment
• Additional audio processing equipment
• Licensing fee(s)
• Qualified technical talent

What if I don’t want or have the money to make our station HD??

There are many FM HD stations broadcasting in markets all across the country. Many of these stations have the equipment in place for multiple HD channels.  In many cases they will lease an HD channel to an organization (I have seen them lease these channels to another radio station) which would allow for an FM translator to be constructed.

Summation

            There is a tremendous amount of information and options for HD radio and we have just skimmed to surface.  In following posts I will break things down further.

Links:

A video developed for DTS (formerly Ibiquity) https://youtu.be/1svvXP6JAfU

The DTS (HD Radio) “How it works” web page https://hdradio.com/what-is-hd-radio